Conductive polyaniline known as emeraldine salt is typically prepared by oxidation of aniline in aqueous acidic media using ammonium persulfate or potassium dichromate. The salt is intractable because of its insolubility and decomposition without melting. However, the undoped (unprotonated) polyaniline known as emeraldines base is not electrically conductive. But the base is slightly soluble in polar solvents such as dimethyl formamide, dimethyl sulfoxide and n-methylpyrrolidinone.
It has been reported that conductive polyaniline prepared in the form of colloidal dispersions using steric stabilizers enhances its processibility. See, for example, Armes, S. P., Aldissi, M., Agnew, S., and Gottesfeld, S., Langmuir, 1990, 6, 1745-1749, and the disclosure of U.S. Pat. No. 4,959,180. Both the chemical and electrochemical synthesis of electrically conducting polyaniline have been described in U.S. Pat. No. 4,940,517. The process of making oriented films of improved conductive polyaniline on the surface of a stretchable support material has also been disclosed in U.S. Pat. No. 4,935,181.
It is an object of this invention to provide methods of producing conductive polymers of improved properties by microemulsion polymerization of the monomers under different conditions.